1. Field of the Invention
The present invention relates to a photoresist stripper composition, and more particularly, to a photoresist stripper composition for forming copper wire structures, a method for forming copper wire structures using the composition, and a method for fabricating a thin film transistor substrate using the composition.
2. Description of the Related Art
Semiconductor integrated circuits, devices, and apparatus play an increasing important role in modern society, and are widely used in many industries. In particular, a growing information-oriented society continually drives the development of new electronic displays, with new display functions being devised and added to meet the ever-diversifying needs of display users. Conventionally, cathode ray tubes (CRTs) have played a major role in the electronic display industry. However, CRTs bear the disadvantages of being heavier, bulkier, and more power-hungry than flat panel displays with a comparable display size. Therefore, flat panel displays such as liquid crystal displays (LCDs), organic electroluminescent (EL) displays, plasma display panels, and the like, are gaining widespread popularity as replacements for CRTs, and a demand is building for large, high-resolution screens.
Certain flat panel displays, such as LCDs and organic EL displays, employ a thin film transistor (TFT) as a switching and/or driving device. A TFT typically is controlled by signals transmitted over a gate line and a data line. The TFT, the gate line and the data line require fine patterns, which are usually formed by a photolithographic etching process using photoresist.
Larger screen displays using fine-patterned TFTs face the challenge of overcoming significant signal delays due to longer signal lines with reduced cross-sectional areas. One solution to this problem is to employ a low-resistivity wire structure. A low-resistivity wire structure typically is made of a material such as copper (Cu) or silver (Ag). In comparison to silver, copper exhibits similar resistivity yet is more cost-effective. However, copper may adhere poorly to an underlying structure, and thus, may be susceptible to separating or peeling off from the underlying structure. Furthermore, even if made to adhere to underlying structures, copper can be susceptible to by oxidation or corrosion by the photoresist stripper materials used to remove photoresist films during the patterning process. Copper degradation reduces the advantages of the copper conductive layer as a low-resistivity wire structure, because it increases the total resistance of the wire structures. Techniques suggested to address these problems have included diluting the photoresist stripper, and reducing the exposure of copper wire structures to a photoresist stripper. However, these techniques may reduce the reliability of copper wiring, because they tend to reduce the stripping capability of a photoresist stripper and allow the formation of a residual photoresist film. Therefore, there is an increasing demand for a photoresist stripper composition exhibiting good stripping capability while suppressing oxidation and corrosion of a copper conductive layer.